Device for detachably engaging an impeller to a shaft



Sept. 24, 1963 P. G. WENDT 3 5 DEVICE FOR DETACHABLY ENGAGING AN IMPELLER TO A SHAFT Filed Oct. 12. 1961 FIG 2 PETER G. WENDT INVENTOR.

BY M W United States Patent Office 3,ltl4,459

3,104,459 DEVICE 1 R DETACHABLY ENGAGING AN IMPELLER TO A SHAFT Peter G. Wendt, Westfield, N..l., assignor to Worthington Corporation, Harrison, N.J., a corporation of Delaware Filed Oct. 12, 1961, Ser. No. 144,632 8 Claims. (Cl. 29252) This invention relates generally to a device for detachably engaging a member on a shaft. More particularly the invention relates to a device for detachably engaging 'an impeller on a shaft when an interference fit is required therebetween.

High speed turbo machinery requires an interference fit between the impeller and the shaft to compensate for the expansion of the impeller bore caused by the centrifugal forces acting thereon. In the past this interference fit was usually a force fit which could cause damage to the impeller especially under field conditions.

It is the object of the present invention to overcome the prior art difliculty while providing the additional advantages described hereinafter.

In accordance with the present invention a novel device is used to mount and remove an impeller on a shaft comprising jack means disposed on the shaft adjacent the outboard end of the impeller in operative engagement therewith. The impeller and the jack means form chamber means about the shaft. A conduit means connects the chamber means to a source of high pressure fiuid and introduces this fluid into the chamber means to compress the shaft and expand the impeller. The jack means and the fluid coact to force the impeller into detachable engagement with the shaft.

One of the objects of this invention is to provide a means for detachably engaging an impeller on a shaft by the novel coaction of jack means and high pressure fluid.

Another object of the invention is to provide for the detachable engagement between the impeller and the shaft in which the damage to the impeller during mounting or removing thereof with the shaft is substantially eliminated.

With this and other objects in view as may appear from the accompanying specification, the invention consists of various features of construction and combination of parts which will be first described in conjunction with the accompanying drawings which show a preferred form embodying the invention and the features forming the invention will be specifically pointed out in the claims.

In the drawings:

FIGURE 1 is a longitudinal view partly in section showing a preferred form of the present invention.

FIGURE 2 is an exploded view of the novel jack means plug and the hollow shaft, which is shown in FIGURE 1.

Referring to the drawings FIGURE 1 shows an impeller 10 disposed on a shaft 11 to which the jack means 12 have been detachably connected.

The impeller has a tapered bore 13 in which a recess 14 is provided near the inner end 15 thereof. An O-ring seal 16 is disposed in the recess 14 for purposes described hereinafter. The outer end 17 of the tapered bore is splined as shown generally at 18.

The shaft is adapted to receive thereon the impeller 10 and the jack means 12 which serves to bring the impeller 10 into detachable engagement with the shaft 11 as hereinafter described.

Thus as shown in FIGURE 1 the shaft 11 has a hollow 19 formed therein and a threaded end section 20. Remote from the end section 20 a shoulder 21 is formed on the shaft 11. Disposed between the end section 20 and the shoulder 21 of shaft 11 has formed thereon a tapered section 22, a splined section 23 and a curvilinear section 24. The tapered section 22 and the splined section 23 of the shaft 11 correspond to the tapered bore 13 and the spline 18, respectively, of the impeller 10 except for the required diametral interference. A support member or plug 25 is disposed in the outer end of the hollow 19 of the shaft 11 for purposes described hereinafter.

The jack means 12 as shown in FIGURE 2 includes the operative association of an annular stationary member 26, an annular movable member 27 and jack screws 28. While the preferred jack means 12 has been shown it is understood that instead of mechanically operated means hydraulic or pneumatic means could suitably be used.

The movable member 27 has a larger internal diameter than the diameter of the end section 20 of the shaft 11 and an inwardly extending flange 29 at the inner end 30 adjacent the impeller 10. This inner end 30 has a recess 31 thereon, in which is disposed an O-ring seal 16. Bores 32 and 33 pass through the member at the top and bottom, respectively, thereof and have threaded counterbores 34 and 35, respectively, and in which therein a threaded retaining plug 36 and a threaded conduit or connecting member 37, respectively, are received in sealed engagement therewith. The connecting member is attached to a hydraulic high pressure system (not shown) for purposes hereinafter described.

The stationary member 26 has a threaded internal section 38 of which part consists of an axially extending flange 39 at the inboard end 40 thereof. This axial flange 39 has an outer diameter substantially equal to the internal diameter of the movable member 27 and is adapted to be slidably disposed therein. At the outboa-rdfend 41 of the stationary member 26 a radially extending flange 42 is disposed having a diameter smaller than the diameter of the hollow 19 of the shaft 11. Flanges 39 and 42 have recesses 43 and 44, respectively, therein in which O-ring seals 16 are disposed. Threaded bores 45 extend axially through the stationary member 26 and have jack screws 28 connected thereto with the inner ends in abutment with the outboard side of the movable member 27 as shown in FIGURE 1. The stationary member 26 may be conveniently screwed onto the threaded end section 20 of the shaft 11 by use of turning bores 46.

Support member or plug 25 has an outer diameter substantially equal to the diameter of the hollow 19' in the shaft 11. However, the outboard section 47 of the plug 25 has a smaller diameter than the diameter of the main section 48 of the plug 25 thereby forming an annular shoulder 49 on the plug 25. A groove 50 is formed in the outboard section 47 of the plug 25 and in which a retaining clip 51 can be disposed. The outboard section 47 of the plug 25 between the shoulder 49 and the groove 50 is of greater axial length than the radial flange 42 of the stationary member 26.

Recesses 14, 3-1, 43 and 44 in which the O-ring seals 16 are disposed are spaced in descending order respectively from the axis of the shaft 11 so that the innermost recess 14 is furthest from the axis and the outermost recess 44 is closest to the axis. Thus the, seals are hydraulically unbalanced in the outboard direction.

When the components are is assembled position as hereinafter described the impeller 10 and jack means 12 form a chamber 52 about the shaft 11 as shown in FIG- URE -1, which chamber 52 is suitably sealed by O-rin seals 16 disposed in recesses 14, 31, 43 and 44. Thus the chamber 52 is adapted to receive high pressure fluid (not shown) from the hydraulic high pressure system (not shown). a e

As pointed out above recess 14 sets the inboard limits of the chamber. 52 and when the impeller 10 and shaft 11 are assembled there is a very minimum clearance 53 therebetween. It could be said that this clearance 53 is created by the high pressure fluid which forces between Patented Sept. 24, 1963 the impeller and shaft 11 thereby compressing shaft 11 and expanding impeller 10.

Thus the interference fit can be accomplished by following the preferred assembly and detachable engagement operations as hereinafter described.

Assembly Operation While the assembly operation is substantially the same for mounting or removing the impeller 10 there is an additional step in the mounting operation, namely that of placing the impeller 10 on the shaft 11 in close engagement therewith. Thereafter the assembly operation is the same and is preferably as follows:

First, the movable member 27 is disposed on the shaft 11 in abutment with the outer end 17 of the impeller 10.

Second, the threaded internal section 38 of the stationary member 26 is connected to the threaded end section 29 of the shaft 11 so that the radial flange 4-2 abuts the end of the shaft 11. Thus the axial flange 39 slidably engages the internal diameter of the movable member 27. Also, the jack screws 28 are rotatably adjusted to abut the outboard end of the movable member 27. The support member 25 being part of the stationary member 26 by means of the retaining clip 51 slides into the hollow 19 of shaft 11 when stationary member 26 is connected to the threaded end section 20 of the shaft 11.

Third, the retaining plug 36 should be removed from the bore 32 at the top of the movable member 27 if disposed therein.

Fourth, the conduit member 37 should be disposed in the bore 33 at the bottom of the movable member 27 if not already disposed therein.

Detachable Engagement Operation The detachable engagement operation follows the assembly operation and has the dual alternate function of either mounting or removing the impeller 10 on or off, respectively, the shaft 11. This is done by introducing high pressure fluid into the chamber 52 from the hydraulic pressure system (not shown) through the conduit member 37 in the bore 33 of the movable member 27. The chamber 52 is filled and thereafter the retaining plug 36 is screwed into the bore 32 of the movable member 27 thereby sealing the chamber 52.

The high pressure fluid is placed under at least enough pressure from the hydraulic pressure system to cause the shaft 11 to compress and the tapered bore 13 of the impeller 10 to expand whereby the diameter of the shaft 11 decreases and the diameter of the tapered bore 13 of the impeller 10 increases. The support member prevents the shaft 11 from being lover-stressed.

It is understood that up to this point there would be substantially no diiference for either the mounting or removing operation, but hereafter the operation differs and therefore We shall first describe the mounting operation.

Accordingly, the jack screws 28 are turned to displace the movable member 27 and the impeller 10 inwardly to force the impeller 10 to seat on the shaft 11. Thereafter the high pressure fluid can be removed from the chamber 52, this followed by the removal of all other assembled parts leaving the shaft 11 with the impeller 10 mounted thereon. The threaded end section 20 of the shaft 11 can be fitted with a suitable nut (not shown) having a smooth exterior so as not to interfere with the impeller operating efficiency.

However, if instead of mounting the impeller 10, its removal is desired the same operation is followed except that the impeller 10 is already mounted on the shaft 11 and the jack screws 28 have to be turned in the opposite direction in order to allow the impeller 19 and the movable member 27 to be displaced outwardly thus unseating the impeller 10 from the shaft 11. It must be remembered that the impeller 10 is slightly hydraulically unbalanced in the outwardly direction. Thus the impeller '10 4 can be removed by using the jack screws 28 to con-tro the outward displacement thereof.

It will be understood that the invention is not limited to the specific construction or arrangement of parts shown but that they may be widely modified within the inven tion defined by the claims.

What is claimed is: a

1. A device for mounting and removing an impeller on and off a hollow ended shaft comprising:

(a) jack means adapted to be disposed on said shaft adjacent the outboard end of said impeller in operative engagement therewith,

(b) said jack means and said impeller to form chainber means about said shaft,

(c) conduit means to connect said chamber means to a source of high pressure fluid and to introduce said fluid into said chamber means to compress said shaft and to expand said impeller,

(a!) support means adapted to be disposed in the out board end of the hollow of said shaft to prevent over- (b) said stationary member detachably mounted on the outboard end of said shaft,

(c) said movable member disposed inwardly of said stationary member in operative engagement with said impeller,

(:1) means for moving said movable member connected to said stationary member in abutment with said movable member,

(c) said moving means and said fluid coasting to force said impeller into detachable engagement with said shaft.

3. The combination claimed in claim 2 wherein:

(a) said stationary member has at least three threaded bores therethrough,

(b) said moving means including at least three jack screws threadedly engaged in the bore of said stationary member in abutment with said movable memher,

(0) said jack screws adapted to move said movable member in operative engagement with said impeller,

'(d) said jack screws and said high pressure fluid coacting to force said impeller into detachable engagement with said shaft.

4. The combination claimed in claim 3 wherein:

(a) said support means comprises a plug means having an outer diameter substantially equal to the diameter of the hollow of said shaft,

(b) said plug means having an outwardly extending outer section of smaller diameter than the diameter of the hollow of said shaft,

(0) said outer section having a groove on the outer periphery thereof, (d) said stationary member having an inwardly extending radial flange of smaller diameter than; the 1 diameter of the hollow of said shaft, (e) said plug means disposed in the hollow of said shaft with the groove in the outer section thereof outward of said flange,

(f) retaining means disposed in said groove to i101 said plug means in assembled position. a a j 5. The combination claimed in claim 4 wherein:

(a) said movable member has port means therein to communicate with saidchamber means,

sure fluid in said chamber means,

(0) said impeller to be expanded and said shaft adapted to be compressed by the high pressure fluid whereby said jack means and the high pressure fluid coact to force said impeller into detachable engagement with said shaft.

6. The combination claimed in claim 5 wherein relied means connected to said chamber means to open during the introduction of pressure fluid medium to allow air to be replaced by the pressure fluid medium and said relief means adapted to be closed thereafter.

7. The combination claimed in claim 6 wherein:

(a) sealing means bound said chamber means,

(b) said sealing means disposed to hydraulically unbalance said pressure fluid medium in the outwardly direction in said chamber means.

8. The combination olaimed in claim 7 wherein:

(a) said shafit has a threaded outer diameter at the outboard end thereof,

(b) said stationary member has a threaded bore inboard of said radial flange and adapted to he connected to said threaded section of said shaft whereby said radial flange abuts the end of said shaft,

(c) said stationary member has an axial flange extending inwardly,

(d) said movable member having an inner diameter substantially equal to the outer diameter of said axial flange of said stationary member and adapted to slidably engage said axial flange in sealed relationship therewith,

(e) said axial flange to prevent radial movement of said movable memiber thereby maintaining the cham- 1 her means leak proof.

References fitted in the file of this patent UNITED STATES PATENTS Tiess et al Oct. 10, 

1. A DEVICE FOR MOUNTING AND REMOVING AN IMPELLER ON AND OFF A HOLLOW ENDED SHAFT COMPRISING: (A) JACK MEANS ADAPTED TO BE DISPOSED ON SAID SHAFT ADJACENT THE OUTBOARD END OF SAID IMPELLER IN OPERATIVE ENGAGEMENT THEREWITH, (B) SAID JACK MEANS AND SAID IMPELLER TO FORM CHAMBER MEANS ABOUT SAID SHAFT, (C) CONDUIT MEANS TO CONNECT SAID CHAMBER MEANS TO A SOURCE OF HIGH PRESSURE FLUID AND TO INTRODUCE SAID FLUID INTO SAID CHAMBER MEANS TO COMPRESS SAID SHAFT AND TO EXPAND SAID IMPELLER, (D) SUPPORT MEANS ADAPTED TO BE DISPOSED IN THE OUTBOARD END OF THE HOLLOW OF SAID SHAFT TO PREVENT OVERSTRESSING OF SAID SHAFT ON SAID SHAFT BEING COMPRESSED, (E) SAID JACK MEANS AND SAID FLUID TO COACT TO FORCE SAID IMPELLER INTO DETACHABLE ENGAGEMENT WITH SAID SHAFT. 